1. Schumacher - his record and consistancy for 16 years speak for themselves. Yeah so he had a few incidents in his career, but every genius is flawed. No one has ever dominated F1 the way he did, not even the great Fangio.
2. Fangio - dominated the sport well into his 40's, an old man in my book!!! Consistant and brave, he was untouchable when he was in a groove.
3. Prost - a race master who let his racing do the talking and not his qualifying. He should have won more WDC, but 4 WDC and 51 wins is still a brilliant track record.